How do I resize multiple objects at once?

So for example I create a graph chart with multiple chart boxes and distances.

Lets say the chart bars are distanced 3 px apart.  

When I drag all of the objects and resize the image while holding shift, it changes all of the distances. 

So when if I start with bars distanced 3px apart and drag and resize the whole thing, some of the bar distances become 1px apart, 2px apart, etc.  WHY????

How do I resize multiple objects while keeping the proportions and distances?

Attached below images, are in the situation I create a "bar chart" and I select the 2nd bar chart drag and select and shrink it while holding the shift, then it turns out like the one very below where the distances are all messed up